Control of a system for access to teletext information

ABSTRACT

A method of controlling a system for providing access to teletext information, comprising, an input for receiving a source signal, a channel selection system for selecting a program channel signal carried by the source signal and including embedded teletext data belonging to a teletext service, a teletext decoder for decoding teletext data embedded in a selected program channel signal, a coder for converting decoded teletext data into a video signal for displaying teletext information on a display device, memory for storing pre-set data including information identifying at least one pre-set program channel signal, an interface for receiving a switch command entered by a user, comprises receiving a switch command through the interface. The method further comprises, in response to the switch command, searching at least a part of decoded teletext data embedded in the pre-set program channel signal for identification information identifying a teletext information provider and directing the system to convert at least part of the decoded teletext data into a video signal if identification information is found corresponding to pre-set identification information included in the pre-set data.

The invention relates to a method of controlling a system for providingaccess to teletext information, which system comprises,

an input for receiving a source signal,

a channel selection system for selecting a program channel signalcarried by the source signal and including embedded teletext databelonging to a teletext service,

a teletext decoder for decoding teletext data embedded in a selectedprogram channel signal,

a coder for converting decoded teletext data into a video signal fordisplaying teletext information on a display device,

memory for storing pre-set data including information identifying atleast one pre-set program channel signal,

an interface for receiving a switch command entered by a user, whereinthe method comprises receiving a switch command through the interface.

The invention further relates to a system for providing access toteletext information, comprising,

an input for receiving a source signal,

a channel selection system for selecting a program channel signalcarried by the source signal and including embedded teletext databelonging to a teletext service,

a teletext decoder for decoding teletext data embedded in a selectedprogram channel signal,

a coder for converting decoded teletext data into a video signal fordisplaying teletext information on a display device,

memory for storing pre-set data including information identifying atleast one pre-set program channel signal,

an interface for receiving a switch command entered by a user, and acontroller for controlling the operation of the system, wherein thesystem is adapted to decode teletext data embedded in the pre-setprogram channel signal upon receipt of the switch command.

The invention also relates to video apparatus comprising such a systemand to a computer program product.

Examples of a method and system as defined above are known, for examplefrom JP-A-06-030386. This publication discloses a teletext receiver inwhich a microcomputer generates a table representing a cross referencebetween four colour keys, a program position (channel) and a page in astorage means. When any of the four colour keys is depressed, a programposition and page data corresponding to the depressed colour key areread from the table of the storage means and stored in a RAM of themicrocomputer. Then the data of the program position are in use tocontrol channel selection of a tuner. Then page data are fed to acharacter signal processor to set a page and to automatically receive ateletext program. The content is displayed on a CRT (Cathode Ray Tube).

A problem of the known receiver is that the viewer has no assurancebefore pressing one of the colour keys, that the page displayed as aresult currently contains information targeted at him.

It is an object of the present invention to provide a method, system,computer program and video apparatus of the types defined above that canbe used as a means for providing access to proprietary information.

This object is achieved by the method according to the invention, whichis characterised by, in response to the switch command, searching atleast a part of decoded teletext data embedded in the pre-set programchannel signal for identification information identifying a teletextinformation provider and directing the system to convert at least partof the decoded teletext data into a video signal if identificationinformation is found corresponding to pre-set identification informationincluded in the pre-set data.

Thus, the identification information identifies proprietary information,i.e. information owned by a private individual or corporation and keptup to date for the benefit of a certain audience. The pre-setidentification information singles out that certain audience. Ifproprietary information is currently available for that audience, it isprovided to them if they provide the switch command.

Preferably, the method comprises, if no corresponding identificationinformation is found, directing the channel selection system to selectat least one further pre-set program channel signal including embeddedteletext data, and searching at least a part of the teletext dataembedded in each further program channel signal for identificationinformation identifying a teletext information provider and directingthe system to decode and convert at least part of the teletext data intoa video signal if identification information is found corresponding tothe pre-set identification information.

Thus, providers of proprietary information are not limited to onechannel. The users of the system controlled by means of this embodimentof the method can be provided with access to a selected number ofdifferent sources of proprietary information.

A preferred variant of this embodiment comprises comprising, ifidentification information is found in teletext data embedded in afurther program channel signal, storing information identifying thefurther program channel signal as starting channel information, andpreferably, in response to a second switch command, directing thechannel selection system to first select the program channel signalidentified by the starting channel information, searching at least apart of the teletext data embedded in the identified program channelsignal for identification information identifying a teletext informationprovider and directing the system to decode and convert at least part ofthe teletext data into a video signal if identification information isfound corresponding to the pre-set identification information. Thus, thesecond time a user requests access to the proprietary information,assuming it is still transmitted embedded in the same program channelsignal, it can be accessed much more quickly, since the first programchannel signal selected is already the correct one.

In a preferred embodiment, wherein the system comprises an input forreceiving at least one further source signal, the method comprises, uponreceipt of the switch signal, directing the system to provide the sourcesignal carrying the pre-set program signal to the channel selectionsystem.

This is a particularly advantageous implementation of the method, as itallows the user quick access to the proprietary information in anenvironment that would otherwise require many actions on the part of theuser, namely selection of the appropriate source, channel and page rangein accordance with up-to-date information which must be at hand to theuser.

A preferred embodiment comprises directing the system to decode andconvert into a video signal teletext data encoding a range of at leastone teletext page, in accordance with pre-set page identification datastored in memory.

Thus, the proprietary information can be reserved for a number ofdedicated pages within the teletext service. In addition, thisembodiment has the advantage that it is not necessary to provide each ofthe pages containing the proprietary data with the identificationinformation. Instead, separately transmitted identification informationindicates to the system that pages containing updated proprietaryinformation are present within the pre-set range.

According to another aspect of the invention, the system according tothe invention is characterised in that the system is adapted to becontrolled by the controller by means of a method according to theinvention.

Thus, the advantages of the method according to the invention areprovided and no external means of control are needed to carry out themethod.

According to another aspect of the invention, there is provided videoapparatus comprising a system according to the invention.

According to a further aspect of the invention, there is provided acomputer program product that, when running on a computing device, iscapable of enabling the computer device to carry out a method accordingto the invention.

The invention will now be explained in further detail with reference tothe accompanying drawings, of which:

FIG. 1 gives a schematic overview at a component level of a system forproviding access to teletext information operating in accordance withthe invention;

FIG. 2 is a flow chart of an embodiment of a method implementing theinvention;

FIG. 3 shows schematically some examples of apparatus employing theinvention.

Two examples of video apparatus that could comprise the system of theinvention are given in FIG. 1. A DVD (Digital Versatile Disk)-recorder 1is connected to a television set 2 by means of an analogue video link.Another suitable piece of video apparatus would be a set-top box. In theexample to be described below, it will be assumed that the invention isimplemented in the television set 2. It is noted that the system forproviding access to teletext information need not be comprised in onediscrete piece of apparatus, but could comprise distributed components.An example of such an implementation is a personal computer with aseparate (possibly external) television tuner connected to a separateboard in the computer, with a teletext decoder chip being fitted to theboard, or with a software teletext decoder being installed on thecomputer. In an alternative implementation of the invention, this systemcould be controlled by software running on the personal computer anddirecting the operation of each of the aforementioned components makingup the system for providing access to teletext information.

Returning to the example of FIG. 1, the television set 2 is controlledby the user by means of a remote control unit 3. Although not necessaryfor the invention, it will be assumed herein that the television set 2is a digital television set. An example of a reference design for adigital television is given in FIG. 2.

The digital television set 2 comprises an input 4 for a digitaltelevision signal, provided, for example by means of a cable, satelliteor terrestrial digital broadcast. The signal may conform to the ATSC orDVB standards, for example. A tuner 5 is used to tune to a broadcastsignal of a certain carrier frequency and to extract an MPEG transportstream. The MPEG transport stream is a multiplex of a number ofelementary streams, of which a number form a program channel signal.

The digital television set 2 can also accept an analogue video signalfrom another source, for example a video recorder or an analoguetelevision tuner, through an analogue input 6. The analogue signal ispassed to a video decoder 7, capable of handling video in one or more ofthe known analogue video formats, e.g. PAL, NTSC or SECAM.

A home entertainment engine 8 processes the incoming transport streamsignals or converted analogue video signals. In addition, the homeentertainment engine 8 controls the operation of the various componentsof the system. Where the incoming MPEG transport stream comprises anumber of program channel signals, it also selects the appropriate oneby de-multiplexing the transport stream. The home entertainment enginefurther comprises a teletext decoder for decoding teletext data embeddedin a program channel signal, i.e. in the signal received from the videodecoder 7 or comprised in an elementary stream of a bouquet of streamsforming a program channel signal and received from the tuner 5.

The home entertainment engine 8 is connected to random access memory(RAM) 9 through a dedicated interface and to a system bus 10 throughanother interface. Also connected to the system bus 10 is an interfaceunit 11, for accepting and converting commands entered by the user bymeans of the remote control unit 3 (FIG. 1).

The home entertainment engine provides an output signal to a videoencoder 12, which converts the output signal into a video signal in aformat suitable for a display device. This may be an RGB-compositesignal for the cathode ray tube of the television set 2. In alternativeembodiments, the term video signal can refer to an MPEG-2 signal for acomputer attached to a monitor, for example. Audio signals are providedby means of an audio encoder 13.

It is noted that the home entertainment engine may have access to othermemory devices than the RAM 9, for example an EEPROM 14, through thesystem bus 10.

According to the invention, a viewer can watch a program on thetelevision set 2, or a general teletext page, and switch to receivingproprietary information by entering a single switch command. Preferably,the command is entered by pressing one single dedicated key 15 on theremote control unit 3. In this context, proprietary information meansinformation targeted at a specific part of the audience, for examplesubscribers. One convenient example concerns the provision of up-to-datecoverage of sports matches, such as games of cricket. Whilst watchinganother program, for example a film, the subscribers to the proprietaryinformation can switch to receiving an updated score by pressing justthe one dedicated key 15.

The switch command is passed by the interface unit 11 to the homeentertainment engine 8 through the system bus 10. In response, the homeentertainment engine executes an algorithm shown schematically in FIG.3.

After receiving the switch command at step 16, the home entertainmentengine 8 consults pre-set data stored in the EEPROM 14. The pre-set dataincludes an entry comprising information identifying a program channelsignal, a range of one or more pages on which proprietary information isbeing transmitted and identification information uniquely identifyingthe provider of the proprietary information.

If a video is being viewed when the switch command is issued, the systemwill first be directed to switch to receiving a source signal from thedigital input 4, rather than the analogue input 6. Then, the tuner 5will be directed to tune to the correct MPEG transport stream and thehome entertainment engine will ensure that the de-multiplexing mechanismit contains extracts the program elementary streams belonging to thepre-set program channel. These streams form a program channel signalfrom which embedded teletext data is extracted and decoded. Thus, afirst pre-set channel is selected in step 17. It is noted that if theproprietary information retrieval facility is being used for the firsttime, the first pre-set channel may simply be the channel that isselected when a key marked ‘1’ on the remote control unit 3 is pressed.In other cases, the first pre-set channel is preferably the channel onwhich the proprietary information has previously been found. In analternative embodiment, the first pre-set channel may have beenspecially programmed by the user of the digital television set 2, orfactory-programmed.

In step 18, the home entertainment engine receives part of the decodedteletext data and searches it for identification informationcorresponding to the pre-set identification information stored in theEEPROM 14. The identification may be included in the headers for thepages identified in the pre-set data Alternatively, the identificationmay be a code in a dedicated packet independent of a particular page,such as packet 8/30 as defined by European Telecommunication StandardETS 300 707. The latter variant has the advantage that the data in thepages is limited to the proprietary information.

If the identification information is found in step 18, then the homeentertainment engine 8 consults the pre-set data stored in the EEPROM 14to retrieve the information identifying a range of one or more teletextpages in which the proprietary information has been inserted. Theteletext decoder is directed to decode these pages. The decoded teletextinformation is provided to the video encoder 12, for output on thescreen of the television set 2, in step 19. Preferably, the proprietaryinformation is included in pages outside the range normally accessible.This means that the pages containing proprietary information will be inthe hexadecimal range, e.g. 10A-10E, 20A-200E, 30A-30E, since the keyson the remote control unit only allow to enter numbers in the range100-109, for example.

If the identification information is not found, then the homeentertainment engine will direct the tuner 5 and de-multiplexingmechanism to select a further pre-set channel program signal in step 20,and repeat step 18. If all pre-set channels have been searched, thealgorithm proceeds to step 21, in which the channel being watched beforethe switch command was received is displayed again. This marks the endof the algorithm.

Preferably, if proprietary information is found on a channel selected instep 20, information identifying this channel is stored. Thus, thesecond time the switch command is entered, the channel identified bythis information will be selected first in step 17.

An alternative embodiment is also feasible, in which, after step 19, theuser may press a further key, for example an ‘up’ or ‘down’ key, toselect a further pre-set channel, which is then searched in a stepsimilar to step 18.

It should be noted that the above-mentioned embodiment illustratesrather than limits the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims. In the claims, any reference signsplaced between parentheses shall not be construed as limiting the claim.The word “comprising” does not exclude the presence of elements or stepsother than those listed in a claim. The word “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.The invention can be implemented by means of hardware comprising severaldistinct elements, and by means of a suitably programmed computer. Inthe device claim enumerating several means, several of these means canbe embodied by one and the same item of hardware. The mere fact thatcertain measures are recited in mutually different dependent claims doesnot indicate that a combination of these measures cannot be used toadvantage.

1. Method of controlling a system for providing access to teletextinformation, comprising: receiving a source signal, selecting a programchannel signal carried by the source signal and including embeddedteletext data belonging to a teletext service, decoding the teletextdata embedded in the selected program channel signal, converting thedecoded teletext data into a video signal for displaying teletextinformation, storing pre-set data including information identifying atleast one pre-set program channel signal, receiving a switch, searchingat least a part of the decoded teletext data embedded in the pre-setprogram channel signal for identification information identifying ateletext information provider and converting at least part of thedecoded teletext data into a video signal if identification informationis found corresponding to pre-set identification information included inthe pre-set data.
 2. Method according to claim 1, comprising, if nocorresponding identification information is found, selecting at leastone further pre-set program channel signal including embedded teletextdata, and searching at least a part of the teletext data embedded ineach further program channel signal for the identification informationidentifying a teletext information provider and decoding and convertingat least part of the teletext data into a video signal if identificationinformation is found corresponding to the pre-set identificationinformation.
 3. Method according to claim 2, comprising, ifidentification information is found in teletext data embedded in afurther program channel signal, storing information identifying thefurther program channel signal as starting channel information. 4.Method according to claim 3, comprising, in response to a second switchcommand, selecting the program channel signal identified by the startingchannel information, searching at least a part of the teletext dataembedded in the identified program channel signal for identificationinformation identifying a teletext information provider and decoding andconverting at least part of the teletext data into a video signal ifidentification information is found corresponding to the pre-setidentification information.
 5. Method according to claim 1, wherein themethod comprises, upon receipt of the switch signal, providing thesource signal carrying the pre-set program signal.
 6. Method accordingto claim 1, comprising decoding and converting into a video signalteletext data encoding a range of at least one teletext page, inaccordance with pre-set page identification data stored in a memory. 7.Video apparatus for providing access to teletext information, comprisingan input for receiving a source signal; a channel selection system forselecting a program channel signal carried by the source signal andincluding embedded teletext data belonging to a teletext service; ateletext decoder for decoding teletext data embedded in a selectedprogram channel signal; a coder for converting decoded teletext datainto a video signal for displaying teletext information on a displaydevice; memory for storing pre-set data including informationidentifying at least one pre-set program channel signal; an interfacefor receiving a switch command entered by a user; and a controller forcontrolling the operation of the video apparatus adapted to decodeteletext data embedded in the pre-set program channel signal uponreceipt of the switch command.
 8. System for providing access toteletext information, comprising: an input for receiving a sourcesignal; a channel selection system for selecting a program channelsignal carried by the source signal and including embedded teletext databelonging to a teletext service; a teletext decoder for decodingteletext data embedded in a selected program channel signal; a coder forconverting decoded teletext data into a video signal for displayingteletext information on a display device; memory for storing pre-setdata including information identifying at least one pre-set programchannel signal; an interface for receiving a switch command entered by auser; and a controller for controlling the operation of the system,wherein the system is adapted to decode teletext data embedded in thepre-set program channel signal upon receipt of the switch command.
 9. Acomputer readable storage medium containing a program which causes aprocessor to perform a method comprising: receiving a source signal;selecting a program channel signal carried by the source signal andincluding embedded teletext data belonging to a teletext service;decoding the teletext data embedded in the selected program channelsignal; converting the decoded teletext data into a video signal fordisplaying teletext information; storing pre-set data includinginformation identifying at least one pre-set program channel signal;receiving a switch command; searching at least a part of the decodedteletext data embedded in the pre-set program channel signal foridentification information identifying a teletext information provider;and converting at least part of the decoded teletext data into a videosignal if the identification information is found corresponding topre-set identification information included in the pre-set data.